The officers formed a moving cordon around the demonstration and there were scuffles as the officers tried to halt the march by linking arms and forming lines. One woman was injured when the officers pushed protesters against a wall near an on-ramp leading to a bridge over the River Nile. But the demonstrators quickly escaped the cordon and marched down the riverside Corniche, snarling traffic.

Now police have started firing tear gas into the crowd. We're following via tweets from local blogger @monasosh and others.